What Exoplanets Might Really Look Like

Early in December, astronomers confirmed the existence of the first known world beyond the Solar System that exists in a cozy, habitable zone around its sun-like star.

It’s too soon to say whether the planet, called Kepler-22b, has a rocky, watery or gassy surface. Nevertheless, NASA used some artistic license to render the planet (below), casting it in a green-blue with wispy white clouds.

Astrobiologist Abel Mendez of the University of Puerto Rico at Arecibo, who is developing new software to render scientifically accurate images of exoplanets, said NASA’s illustration misses the mark.

“I think that the NASA image got the color right,” Mendez said, “but I don’t expect clouds like that. It probably will be more featureless like Uranus or Neptune and not so good for a press release.”

To Mendez, it’s more than an artistic quibble. Since the Kepler telescope launched in March 2009, the space-based observatory has pinpointed a whopping 2,326 exoplanet candidates, and that number is growing by about 70 planets a month.

It’s an untenable situation for space artists, whose renderings often lack the accuracy informed by current planet formation theories. More importantly, said Mendez, databases of scientifically informed portrayals of unseen exoplanets — including animations — could help make sense of direct future observations.

If these portrayals are shrunk to tiny points of light — resembling some of the direct exoplanet images obtained by astronomers so far — the pictures could hint at the planets' conditions.

“You could render how the point of light oscillates and changes. When you see the light for the first time, you could know right away what you’re looking at,” Mendez said. “You could say, ‘this is a planet with this much cloud cover, is covered by this much ocean and rotates like this.’”

Although he hasn't yet imaged Kepler-22b, he has rendered 16 of 48 other potentially habitable exoplanet candidates discovered by the Kepler space telescope and ground-based telescopes.

Astronomers need only a few pieces of information to use the software, such as the distance an exoplanet orbits from its star, the temperature and radius of the star and the exoplanet’s radius or mass. The software then uses leading planet formation theories to produce detailed renderings of the distant world.

The software can tackle everything from scorching-hot gas giants larger than Jupiter to rocky worlds smaller than Earth and render color-accurate atmospheres, oceans, lakes and land masses. It can even cut animated videos of rotating planets if given ample computer processing time.

Wired.com offered to take the program for a spin, but Mendez said it’s an alpha release that’s not ready for public eyes — even most astronomers won’t get to try until March or April of 2012.

When Mendez’ team of about 10 people release the program, however, he said they’ll start working on a more streamlined version that anyone can use.

“Perhaps even Hollywood,” Mendez said.

On the following pages, Wired looks at the Scientific Exoplanet Renderer's planetary visions.

Customization

Beyond the basic parameters available in Kepler’s exoplanet database, astronomers can improve the illustration with their own observations.

“Let’s say you get some new observations that suggest there’s a lot of water there,” Mendez said. “You can plug that in and create a better rendering on your own.”

Image: Planetary Habitability Laboratory at UPR Arecibo

Red Earth?

To harbor life, some planets may not need a sun like our own -- a star that astronomers classify as a G-type. A planet close enough to a cooler red dwarf star may be plenty warm to support dark-hued life.

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